Chemoenzymatic synthesis of novel siderophore scaffolds

新型铁载体支架的化学酶法合成

• 批准号: 2883889
• 金额: --
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2883889
• 关键词: Chemoenzymatic; synthesis; novel; siderophore; scaffolds

Iron is an indispensable cofactor for all microbial life. The ability to coordinate and activate molecular oxygen, in addition to optimal redox properties for electron transport, places it central to numerous cellular processes. It is therefore vital that iron homeostasis is carefully managed. Although iron has a high natural abundance, it exists predominantly as Fe3+ in aerobic environments and tends to form insoluble ferric hydroxides rendering it inaccessible to microorganisms. Organisms have therefore evolved complex strategies for iron acquisition and storage. Whilst several mechanisms are known, a common approach employed by bacteria and fungi is the production of low-molecular-weight compounds known as siderophores, which serve as high-affinity iron chelators. In fungi, the majority of siderophore compounds produced belong to the hydroxamate class. This functionality originates from L-ornithine, which is N5-hydroxylated and subsequently N5-acylated to yield a bidentate ligand. Typically, siderophores possess three hydroxamate units, producing a hexadentate ligand, which promotes formation of a polyhedral Fe3+ complex with binding constants in the 1022 - 1032 range. Whilst the physiological function of hydroxamate siderophores in fungi is well established, the molecular details of their biosynthesis remain poorly characterised. Genes encoding for large non-ribosomal peptide synthetase (NRPS) enzymes are known to be responsible for the assembly of peptidyl siderophores. Recent work on the SidD NRPS, responsible for the biosynthesis of the siderophore fusarinine C, revealed a highly unusual nonlinear behaviour to construct the depsipeptide siderophore structure. These included observations of inter-module loading of amino acids and an iterative cycle of chain extension reactions.The biosynthetic gene cluster in Penicillium rubens responsible for fusarinine C, shares very similar domain architecture to that of coprogen. It also shares a similar substrate, anhydromevalonyl-hydroxyornithine, although coprogen is made from the trans isomer rather than the cis. Despite the similarity of domains and substrate, a very distinct product structure, coprogen, is formed. This PhD projects aim is to characterise the biosynthetic pathway responsible for coprogen production, elucidate the molecular details in the biosynthesis of the trans monomeric unit and the full depsipeptide, and to determine the 3D structure of the NRPS enzyme complex.

铁是所有微生物生命不可或缺的辅助因子。除了电子传输的最佳氧化还原特性之外，协调和激活分子氧的能力使其成为许多细胞过程的核心。因此，仔细管理铁稳态至关重要。尽管铁的自然丰度很高，但它在有氧环境中主要以 Fe3+ 形式存在，并且往往会形成不溶性氢氧化铁，使其无法被微生物接触。因此，生物体进化出了复杂的铁获取和储存策略。虽然已知多种机制，但细菌和真菌采用的常见方法是产生称为铁载体的低分子量化合物，其充当高亲和力的铁螯合剂。在真菌中，产生的大多数铁载体化合物属于异羟肟酸盐类。该功能源自 L-鸟氨酸，其被 N5-羟基化，随后被 N5-酰化以产生双齿配体。通常，铁载体具有三个异羟肟酸单元，产生六齿配体，促进形成结合常数在 1022 - 1032 范围内的多面体 Fe3+ 复合物。虽然真菌中异羟肟酸铁载体的生理功能已得到充分证实，但其生物合成的分子细节仍知之甚少。已知编码大非核糖体肽合成酶（NRPS）的基因负责肽基铁载体的组装。最近对负责铁载体镰刀菌素 C 生物合成的 SidD NRPS 的研究揭示了构建缩酚肽铁载体结构的极不寻常的非线性行为。这些包括对氨基酸模块间加载和链延伸反应迭代循环的观察。红青霉中负责镰孢菌素 C 的生物合成基因簇与粪原的结构域结构非常相似。它也有一个相似的底物，脱水甲羟戊酸羟基鸟氨酸，尽管 coprogen 是由反式异构体而不是顺式异构体制成的。尽管结构域和底物相似，但形成了非常独特的产物结构，coprogen。该博士项目的目的是表征负责粪原产生的生物合成途径，阐明反式单体单元和完整缩酚肽生物合成的分子细节，并确定 NRPS 酶复合物的 3D 结构。